Jordan Spieth hits a shot on the third hole during a practice round for the PGA Championship golf tournament Wednesday, Aug. 12, 2015, at Whistling Straits in Haven, Wis. (AP Photo/Brynn Anderson)
(The Associated Press)

Jordan Spieth makes his way to the first tee during a practice round for the PGA Championship golf tournament Wednesday, Aug. 12, 2015, at Whistling Straits in Haven, Wis. (AP Photo/Chris Carlson)
(The Associated Press)

About his ankle. About the state of the game. And then there was one question he had trouble answering Wednesday on the eve of the PGA Championship.

Who's the best player in the world?

McIlroy remains No. 1 in the world ranking. He also has watched Jordan Spieth produce one of the most memorable years in golf by winning the Masters and U.S. Open, and coming within one shot of a playoff at St. Andrews for the third leg of the Grand Slam.

They face off Thursday at Whistling Straits, playing in the same group with British Open champion Zach Johnson.

McIlroy says there are no indications his game has slipped during his 53 days off from competition.